9 ms·

I also wonder about rogue planets near the galactic center. They wouldn't need to have their own star to get bathed in plenty of light from other nearby stars.

by RIMR 12y ago

I also wonder about rogue planets near the galactic center. They wouldn't need to have their own star to get bathed in plenty of light from other nearby stars. There would be no such thing as night and day either.

bjwbell 12y ago
There is too much radiation... for life as we know it on those planets.
- kijin 12y ago
  Water is pretty good at blocking radiation [1]. Life could exist in a layer of the ocean where ionizing radiation is reduced to a survivable level but plenty of visible light gets through. Or the planet could be teeming with water bears. [1] https://what-if.xkcd.com/29/ https://what-if.xkcd.com/29/
nsajko 12y ago
I think the galactic bulge probably doesn't support life because of ionizing radiation and unstable orbits.
Retra 12y ago
You might be underestimating the distance between stars in the galactic center...
- Crito 12y ago
  It isn't a great source, but this seems to suggest it would actually be pretty significant: > "Near the galactic center, the average distance between neighboring stars would be only 1000 AU (about a light-week). If the Sun were located within a parsec of the galactic center, there would be a million stars in our sky with apparent brightness greater than Sirius. The total starlight in the night sky would be about 200 times greater than the light of the full moon; you could easily read the newspaper at midnight, relying on starlight alone." http://www.astronomy.ohio-state.edu/~ryden/ast162_7/notes31.html http://www.astronomy.ohio-state.edu/~ryden/ast162_7/notes31....
- gambiting 12y ago
  Obviously this is not a perfect comparison, but even on Earth, if the night is cloudless, you are away from any cities, and the moon is not visible, the stars provide some light. Not bright enough to see clearly, but you can see a little bit, even with our weak human eyes. So I imagine that even on a planet without a star it wouldn't be 100% dark, there would be some light.
spartanatreyu 12y ago
Just think about the early universe, a rouge planet would only need a sufficiently thick atmosphere. The universe itself would have been so hot that liquid water would have existed without a star's heat.
- cozzyd 12y ago
  I don't think the early universe had sufficient amounts of heavy elements to form planets... everything heavier than lithium is made by stars.
  - x3n0ph3n3 12y ago
    Not entirely true. Everything heavier than Boron is made by stellar nucleosynthesis: http://en.wikipedia.org/wiki/Cosmic_ray_spallation#/media/File:Nucleosynthesis_periodic_table.svg http://en.wikipedia.org/wiki/Cosmic_ray_spallation#/media/Fi...

by RIMR 12y ago

bjwbell 12y ago

There is too much radiation... for life as we know it on those planets.

kijin 12y ago
Water is pretty good at blocking radiation [1]. Life could exist in a layer of the ocean where ionizing radiation is reduced to a survivable level but plenty of visible light gets through. Or the planet could be teeming with water bears. [1] https://what-if.xkcd.com/29/ https://what-if.xkcd.com/29/

nsajko 12y ago

I think the galactic bulge probably doesn't support life because of ionizing radiation and unstable orbits.

Retra 12y ago

You might be underestimating the distance between stars in the galactic center...

Crito 12y ago
It isn't a great source, but this seems to suggest it would actually be pretty significant: > "Near the galactic center, the average distance between neighboring stars would be only 1000 AU (about a light-week). If the Sun were located within a parsec of the galactic center, there would be a million stars in our sky with apparent brightness greater than Sirius. The total starlight in the night sky would be about 200 times greater than the light of the full moon; you could easily read the newspaper at midnight, relying on starlight alone." http://www.astronomy.ohio-state.edu/~ryden/ast162_7/notes31.html http://www.astronomy.ohio-state.edu/~ryden/ast162_7/notes31....
gambiting 12y ago
Obviously this is not a perfect comparison, but even on Earth, if the night is cloudless, you are away from any cities, and the moon is not visible, the stars provide some light. Not bright enough to see clearly, but you can see a little bit, even with our weak human eyes. So I imagine that even on a planet without a star it wouldn't be 100% dark, there would be some light.

spartanatreyu 12y ago

Just think about the early universe, a rouge planet would only need a sufficiently thick atmosphere. The universe itself would have been so hot that liquid water would have existed without a star's heat.

cozzyd 12y ago
I don't think the early universe had sufficient amounts of heavy elements to form planets... everything heavier than lithium is made by stars.
- x3n0ph3n3 12y ago
  Not entirely true. Everything heavier than Boron is made by stellar nucleosynthesis: http://en.wikipedia.org/wiki/Cosmic_ray_spallation#/media/File:Nucleosynthesis_periodic_table.svg http://en.wikipedia.org/wiki/Cosmic_ray_spallation#/media/Fi...